National Botulism Reference Laboratory

National Botulism laboratory, Penn VetThe National Botulism Reference Laboratory at New Bolton Center provides diagnostic services for both suspected individual cases of botulism, as well as possible outbreaks.

As one of the few laboratories of its kind in the United States, the laboratory provides testing for samples from multiple animal species including equine, bovine, avian and canine, as well as suspected feedstuffs and forages.

Leading experts in clinical botulism are available for consultation to discuss clinical signs of affected animals, as well as epidemiological factors in order to determine the likelihood of a single case of botulism, or to help identify an outbreak.


Available Botulism Assays

Botulinum Toxin: Direct detection of botulinum toxin is performed using a mouse bioassay.  The test can be performed on feed samples, or on serum or gastrointestinal contents of patients.  The toxin has low stability in the GI tract, and horse and bovine serum are rarely positive except for severe, per-acute cases.  The test is most useful for evaluating feed samples, and serum from birds or dogs.  We recommend instead the organism/spore testing for GI samples from equine and bovine patients. This test has a turn-around time of up to one month, as samples are held and run in batch monthly. 

Organism/Spore Detection:  Assay for Clostridium botulinum organisms or spores in feed samples or GI samples (feces, stomach, intestinal content) is performed using a real-time PCR assay for the detection of Clostridium botulinum types A, B or C, after culture enrichment of the sample.  Since the PCR assay detects the toxin genes of C. botulinum, any PCR positive samples are followed-up with the mouse bioassay to confirm toxin elaboration by the organisms in culture.  Finding C. botulinum organisms or spores in a fecal or GI sample of a horse or cow is strongly supportive of a diagnosis of botulism in animals exhibiting compatible clinical signs… normal animals are rarely positive.  Expected turn-around time for culture/PCR results is approximately 1 week.  Mouse bioassay follow-up requires an additional 2-3 weeks.

Cost of Diagnostic Testing per Sample

  • Mouse assay only for toxin:  $75/sample. 
  • PCR for organism/spores with mouse follow-up of PCR-positives: $150/sample
  • Both assays (i.e pre-formed toxin, and organisms/spores): $225
  • There is also an accession fee of $25 for each group of samples submitted. 

An invoice is sent to the submitting veterinarian upon receipt of the samples.

Samples to Submit

It is recommended that you call the lab to discuss ideal sample type and test before submitting samples. The best samples to submit for botulism testing are generally stomach/rumen contents, GI contents, feces, serum, spoiled forages, parts of dead animals found in suspect feed, and soil from underneath affected areas.  

Serum samples (need 5-8 mls), are rarely of value in horses and cattle unless the clinical signs have a peracute onset and progression of clinical signs.  Serum samples from dogs and birds are more likely to be positive for toxin, since these species are more resistant to botulism.  If serum is sent, please send as much as possible (4-5 mls) and do not use EDTA tubes.

How Samples should be packed


Approximately 2 ounces of liquid or 20 grams of solid sample is ideal for testing.  Samples should be sent in whirl pack bags or other suitable small leak proof container.  Put each intestinal sample (contents only, please don’t send whole intestines or intestines tied off on either end) in a separate Whirlpak bag and clearly label with ID with a waterproof marker such as a Sharpie.


As much serum as possible should be submitted.  The larger amount of serum, the better the chance for detection of preformed botulinum toxin in mice.  Serum should be spun down, separated, and frozen prior to shipping.  If there is no centrifuge available, send blood in red top collection tubes (unfrozen) with ID clearly labeled with a waterproof marker such as a Sharpie.

Storage and Shipping of Diagnostic Samples

If Samples are fresh and are to be sent immediately:  
Pack in Styrofoam box with ice packs and send Standard Overnight via UPS or FedEx. 

If Samples will not be sent immediately:  
Please store in freezer until ready to send, and then follow the instructions above.  

What to Include with Samples

Please include along with the samples a completed Submission Form with a detailed clinical history including the number of animals affected, number showing clinical signs, number dead, progression of clinical signs, treatment of the animals, the suspected source, results on any other tests ran on the animals, etc.   If available, a copy of the letter from the referring veterinarian would also be appreciated.  If the animal has been necropsied, please attach a copy of the necropsy report.

Where to Send Samples

  Sending Samples
  Where to Send Samples Laboratory Contact Information
 Attention:  Botulism Laboratory
New Bolton Center
382 West Street Road   
47 Myrin Building
Kennett Square, PA 19348
Susan C. Gallagher
Research Specialist
Ph: 610-925-6383
Fax: 610-925-6807
NOTE:  Do not send samples on either Fridays or Saturdays, as no one will be in the Lab over the weekend to receive them.

Contact Information
  Type Name
 Title Contact Information
 Laboratory Susan C. Gallagher, BS
 Botulism Research Technician

 Ph: 610.925.6383

Email: susancg@vet.upenn.edu 

  Case Consultations
 Robert H. Whitlock, DVM, PhD

 Emeritus Professor of Medicine

 Ph: 610.960.2843

Email: rhw@vet.upenn.edu

 Case Consultations  Raymond Sweeney, VMD

 Director, National Botulism Reference Laboratory

Professor, Medicine 

Ph: 610.925.6132

Email: rsweeney@vet.upenn.edu

 Case Consultations  Amy Johnson, DVM
 Assistant Professor, Neurology

 Ph: 610.925.6283

Email: amyjohn@vet.upenn.edu